Ground Loop.. I hate you.

[Blazin]

Alright, so as some of you know I've been dealing with a ground loop for some time now..

I stepped back from the problem as I had plenty of time to deal with it.. I finally did the following:


- I've moved my Receiver and Computer to a different location that would isolate them from my other components.

- I have removed ALL connections other than the VGA connector from my TV(the monitor as I am doing this from my media center location)

- Connections:

TV<->Computer : VGA DBsub
Computer<->Wallin's : RCA to 1/8" jack
Computer<->Receiver : RCA to 1/8" jack
Receiver<->Wallin's : speaker wire

TV, Computer, and Receiver are all disconnected from anything other than the power and signals required for SynRTA Freq Response measurement.

TV, Computer, and Receiver are all powered by the same outlet by use of a surge strip.

I read through some threads, saw a quick fix could be a cheater plug, Cheater plug placed on computer(only 3 prong)... NO FIX

Soundcard removed from Computer and use of onboard audio... NO FIX

Tried both 'A' and 'B' Speakers from reciever... NO FIX

In my previous thread I've stated that a loop back on the sound card shows no sign of 60Hz harmonics..

AS SOON AS A CONNECTION IS MADE TO THE RECIEVER 60HZ and Harmonics appear...

Someone help me.. now its becomming obvious there is some issue with the reciever or Wallin's jig... I believe I tested using the wallin's without the reciever in the loop.. I'll double check on that..


If it is my receiver.. what do I do?


Note:

I noticed that when using DSP settings on 'A' Speakers, 60 Hz and Harmonics have small bandwidths essentially (with the low resolution of SynRTA) directly at 60Hz or the harmonice; however, with 'direct' setting the 60Hz peak has a much larger bandwidth almost appearing to span 40-80 hz..



At this point I'm ready to throw my enclosure in my car and drive to anyone's house that has a measurement setup that performs properly.. you just have to promise not to make fun of my cabinet building proficiency - haha.

[---k---]

CJD probably has his setup this weekend and is taking measurements, just north of Chicago.

I'm surprised the cheater plug didn't solve it. I would probably add a cheater plug to every single piece of gear you've got. See if that solves it. Then, you can work on removing them and really solving the problem. Maybe it is time for a Jensen transformer somewhere in there.

And, you are plugging everything into the same power strip, right?

[Blazin]

CJD probably has his setup this weekend and is taking measurements, just north of Chicago.

I'm surprised the cheater plug didn't solve it. I would probably add a cheater plug to every single piece of gear you've got. See if that solves it. Then, you can work on removing them and really solving the problem. Maybe it is time for a Jensen transformer somewhere in there.

And, you are plugging everything into the same power strip, right?

I only need one cheater because the receiver and the tv don't have 3 prongs..

and yes they are all in the same strip..

haha and I'm not driving to chicago.. thats just silly.. but Bostonish area would be awesome

[mpotoka]

DId you try disconnecting the monitor from the computer? I finally traced my ground loop to my projector..... just a thought

[Blazin]

DId you try disconnecting the monitor from the computer? I finally traced my ground loop to my projector..... just a thought

I'll try again later using a Monitor, if your suggesting my TV could be causing the problems..

[augerpro]

DId you try disconnecting the monitor from the computer? I finally traced my ground loop to my projector..... just a thought

Also does it stop when you disconnect the comp from the reciever AND teh tv from the receiver? You don't have cable still connected to the tv do you?

[Blazin]

Also does it stop when you disconnect the comp from the reciever AND teh tv from the receiver? You don't have cable still connected to the tv do you?

When doing these tests I only had the PC DSUB connector plugged into the TV... I unplugged the HDMI cables used for DTV signal and DVD Player, component cables for Game system, and any other unnecessary cables.

I was running these tests bare minimum... the 60Hz and harmonics stop as soon as the computer is disconnected from the receiver, IE the Line out on computer to RCA input on the receiver is unplugged.. the receiver is the cause I believe...


IS there an easy way to run a full loop using the reciever without using Wallin's jig?

[augerpro]

Hmmm I would be more inclined to blame the comp, they are noisy little things. But who knows.

I don't how safe it would be to run a loopback without the jig. the voltage divider protects the soundcard input from frying. Why would you want to remove just jig anyway?

[ThomasW]

If you're only running stereo out from the PC, get a Behringer SRC2496. Use it to convert the signal to a toslink output, doing that will break any ground loop

[impala454]

There are plenty of cheap sound cards out there with toslink as well.

[max_andrews]

Try buying a cheap UPS power strip and plug your computer into that. Since It's basically a battery and an inverter, there are fewer ground problems and the computer is effectively running on a different circuit from the house power. You can get a cheap one for ~$50 from best buy/etc., give it a shot and if it doesn't work return it.
Is your somputer a laptop or desktop? You could also try putting in a newer power supply if it's a desktop.

[jquin]

An alternative to using toslink is to use an audio transformer between the soundcard and receiver, but to be honest the best way would be to get a toslink sound card.
The transformers can add distortion of their own.

[Inu_Yasha]

I actually had a bad ground loop problem up until an accident that I stumbled across this semester (I'm in college :P). Basically I had a bad ground loop with my sub. Turns out, the issue was with matching grounds...

What I mean by that is that I had 3 components hooked up to my sub: a EP2500 amp, a BFD, and a cleanbox. The EP2500 and BFD had three prong connectors and the cleanbox had 2 prongs. What made my ground loop disappear was using a cheater plug on the EP2500 and BFD, then hooking them both to a power strip. I then hooked up the cleanbox to a power outlet of its own. Since then I haven't had any more hum. Any other power configuration gives lots of ground loop, but that config has none. I'm thinking that either having grounded plugs plugged into a grounded power strip or having a non grounded plug plugged into the grounded outlet gave rise to the hum. Hopefully this makes sense and will help you some :P

[Blazin]

WHOA WHOA WHOA..

I'm an idiot.

Can I output TOSLINK with Speaker Workshop?

I already have a TOSLINK soundcard. lol

[ThomasW]

Can I output TOSLINK with Speaker Workshop?

Nows the time to find out....

[Blazin]

Nows the time to find out....

Yea, I asked, then I tried, then I punched myself in the head...


Because SW outputs through Toslink just fine, and of course that eliminates the groundloop..



I ass-umed that SW could not output through TOSLINK properly as it uses R-L Channels differently, my assumption was incorrect because in the end.. TOSLINK>Receiver>Speaker wire>Wallin's>RCAtoMiniJack>Line in looks like an arbitrary input signal


Way to go SW for futureproof software.


Way to fail at life me.


Haha thanks everyone!

[digital desire]

I may have missed it but, do you have cable tv or antenna hooked up to the system?

[---k---]

I'm pretty he said he unhooked it. But yeah, Cable TV / Sat. is the biggest offender. I got an issue with mine that i haven't spent the time to fix.